This invention relates to methods and apparatus for cleaning photoconductive surfaces and is specifically directed to such cleaning operations involving the removal of developer material where toner particles are suspended in a liquid dispersant.
Heretofore, practitioners in the liquid toner transfer art, when concerned with cleaning operations, have developed a variety of rotary sponge cleaning mechanisms. Such rotary sponge cleaning mechanisms have been utilized either by themselves or in combination with cleaning blades (i.e. doctor blades) which engage the photoconductive surface after the surface has been subjected to the scrubbing or particle loosening action of the rotary sponge means.
Such mechanisms, all to often, tend to induce scratching of the sensitive photoconductive surface. Moreover, removed toner particles tend to accumulate on the cellular surfaces of rotary cleaning sponges. Such accumulated toner particles tend to dry on such rotary cleaning sponges after a copying operation has been completed, and thus provide a coarse, dried particle surface which is likely to cause drum scratching when the machine is used for subsequent photocopying operations.
The present invention is specifically designed to avoid such drum scratching tendencies and entails, in one preferred format, the following cleaning method aspect:
providing elastically yieldable roller means having a smooth, yieldable periphery adjacent the periphery of a photoconductive surface;
moving the photoconductive surface so as to carry a layer of developer, comprising toner particles dispersed in a gelatex dispersant, generally toward the yieldable roller means;
applying a lubricating liquid to the developer layer;
pressing the yieldable roller means against the developer layer with its axes being parallel to the photoconductive surface and with
the smooth yieldable periphery of the elastically, yieldable roller means being arcuately deformed into concave, smooth faced pad means penetrating the developer layer to a depth such that the concave smooth faced pad means is generally spaced from the photoconductive surface by a distance not exceeding the diameter of the minimum sized particles of the toner; PA1 the rotation being operable to apply a shearing force to the gelatex dispersant operable to reduce the viscosity thereof; PA1 the rotating yieldable sponge means being operable to remove toner particles from the developer layer;
rotating the elastically yieldable roller means so that its periphery moves at a speed at least equal to the speed of the moving photoconductive surface but in a direction opposite thereto, with
maintaining a gap between the concave, smooth faced, pad means and the photoconductive surface, with the gap having a thickness not exceeding the diameter of the minimum sized toner particles;
scrubbing the photoconductive surface with rotary, yieldable sponge means before the developer layer is engaged by the concave pad means, with
causing the rotating, yieldable sponge means to peripherally engage the rotating, elastically yieldable roller means and remove toner particles from the rotating, elastically yieldable roller means; and
applying doctor blade means to the periphery of the rotating, elastically yieldable roller means so as to remove toner particles therefrom;
the lubricating fluid being applied to the developer layer between the rotating, yieldable sponge means and the rotating, elastically yieldable roller means and being operable to tend to flush at least some of the removed toner particles from the photoconductive surface; and
the rotating, yieldable sponge means being compliantly engaged with the doctor blade means and operable to separate toner particles accumulated thereon.
Another independently significant aspect of the invention involves a method as above described not limited to cleaning operations involving gel-like materials or to the yieldable nature of the smooth cleaning roller.
A further independently significant aspect of the invention involves cleaning operations where the auxiliary, rotating yieldable sponge means is not necessarily employed.
Yet another independent method aspect of the invention involves the method aspect initially described, not limited to use with gel-like materials and not necessarily including the use of the auxiliary, rotating, yieldable sponge means.
As will be appreciated, each independently significant method aspect of the invention is related to a corresponding apparatus which includes means for implimenting the steps of each independently significant method facet of the invention.
In describing the invention, reference will be made by example, but not by way of limitation, to a presently preferred embodiment.
The presently preferred embodiment is illustrated in appended drawings which will now be described.